Laser printers have become very popular, especially where fast printer output is desired. Other types of printers that operate on the same principle as laser printers, such as printers that utilize light-emitting diodes (LED's) instead of lasers, are also available and have become popular. A laser printer generally works as follows. An image transfer roller, which may also be referred to as a photoreceptor drum, a photoconductor drum, an organic photoconductor, an optical photoconductor, or a photoconductor, is pre-charged using a charge roller or corona wire. A laser then writes the desired image onto the photoconductor, electrostatically discharging the photoconductor according to the desired image. Meanwhile, a toner transfer roller, or developer roller, is coated with charged toner from a toner hopper, or toner cartridge sump.
Traditionally, laser printers maintained a small gap between the photoconductor and the developer roller and/or the charge roller. This is especially the case with black-and-white laser printers. However, more recently laser printers have had the photoconductor come into contact with the developer roller and/or the charge roller.
Photoconductors can be relatively hard, however. Therefore, if the relatively soft developer and/or charge rollers remain in contact with them constantly, especially during shipment of toner cartridges of which the photoconductors and these rollers are a part, these rollers can go out of round, developing flat spots. Such deformation of the rollers can result in image quality degradation. At best, the rollers regain their round shape over time, and image quality improves. At worst, though, the rollers retain their deformed shape, and image quality may not improve.
Furthermore, the photoconductors may develop what is referred to as rub memory if the developer and/or charge rollers remain in contact with them constantly. Rub memory is the build up of a charge onto the surface of a photoconductor, due to constant contact with the rollers. This build up of charge is exhibited in the images formed on media by repeating lines throughout the image. At best, the rub memory dissipates over time, and the repeating lines cease. At worst, however, the rub memory does not dissipate, and the repeating lines do not stop.